Method of making opacifying articles

ABSTRACT

An opacifying article can be made using a (i) fabric having a face side and a back side and an (ii) opacifying element having a substrate that has first and second opposing surfaces; and a dry opacifying layer that has an inner surface and an outer surface. The dry opacifying layer is disposed with its inner surface in contact with the first opposing surface of the substrate. The dry opacifying layer has (a) 40-90 weight % of porous particles, each having a continuous polymeric phase and discrete pores dispersed within the continuous polymeric phase. The porous particles have a mode particle size of 2-50 μm and a porosity of 20-70 volume %. The dry opacifying layer also contains (b) 10-60 weight % of a binder material. The (ii) opacifying element is laminated to the back side of the fabric to provide the opacifying article.

RELATED APPLICATION

Reference is made to the following related application: U.S. Ser. No.15/______ filed on even date herewith by Nair and Brick, entitled“Opacifying Articles” (Attorney Docket K002232/JLT), the disclosure ofwhich is incorporated herein by reference.

FIELD OF THE INVENTION

This invention relates to the field of light-blocking materials toprovide shades, blinds, or other opacifying articles to block ambientlight. In particular, this invention relates to methods for formingopacifying articles that are prepared by laminating an opacifyingelement containing porous particles to a fabric.

BACKGROUND OF THE INVENTION

In general, when light strikes a surface, some of it may be reflected,some absorbed, some scattered, and the rest transmitted. Reflection canbe diffuse such as light reflecting off a rough surface like a whitewall, in all directions, or specular, as in light reflecting off amirror at a definite angle. An opaque substance transmits almost nolight, and therefore reflects, scatters, or absorbs all of it. Bothmirrors and carbon black are opaque. Opacity depends on the frequency ofthe light being considered. “Blackout” or light blocking materialstypically refer to coated layers in articles that are substantiallyimpermeable to light such as visible and UV radiation. Thus, when ablackout material such as a blackout curtain or blackout shade is hungover a window, it generally blocks substantially all external light fromentering the room through that window. Blackout materials are suitableas curtains or shades for use in homes, for institutional use inhospitals and nursing homes, as well as for use in commercialestablishments such as hotels, movie theaters, and aircraft windowswhere the option of excluding light can be desirable.

Light blocking articles such as the blackout curtains can be comprisedof a fabric (porous substrate) coated with several layers of alight-blocking composition. There is a need for these curtains, inaddition to blocking transmitted light, to have a light color (hue)facing the environment to aid in illumination to minimize the amount ofartificial lighting needed to perform the activity. An example is whenthe function of the blackout material is to separate two areas ofactivity where one or both areas can be artificially lit at the sametime. More often than not, the function of a blackout curtain is toprevent sunlight from entering a room through a building window. It canalso be desirable for the color (hue) of the side facing the window tomatch the exterior decor of the building.

Light colored blackout curtains theoretically can be made by coatingporous fabrics with light colored foams containing light scatteringpigments such as titanium dioxide or clays. However, very thick foamcoatings will be needed to create blackout curtains through which thesun is not visible in a darkened room using only these pigments. Onemethod that is practiced for reducing the weight of such blackoutmaterials is to sandwich a light-absorbing, foamed black or greypigment, such as a carbon black between two foamed light scattering,white pigment-containing layers.

When an electromagnetic radiation blocking coating has, as it oftendoes, a strongly light absorbing material containing black pigments suchas carbon black, between two reflective layers, it has at least twodistinct problems. First, such materials require three or more separatecoating operations that reduce manufacturing productivity and increaseunit costs. Secondly, carbon black in the light absorbing middle layercan become “fugitive” (or non-enclosed) from some puncture or tearoccurring during sewing or laundering, and soil other layers such as thereflective layers, which is highly objectionable. Additionally, thestitches generated in the materials during sewing can cause the fugitivecarbon black from the light absorbing layer to spread over a larger areathereby increasing the area of objectionable shading of thelight-colored surface.

U.S. Pat. No. 7,754,409 (Nair et al.), U.S. Pat. No.7,887,984 (Nair etal.), U.S. Pat. No. 8,252,414 (Putnam et al.), and U.S. Pat. No.8,329,783 (Nair et al.) describe porous polymer particles that are madeby a multiple emulsion process that provides formation of individualporous particles comprising a continuous polymer phase and multiplediscrete internal pores, and such individual porous particles aredispersed in an external aqueous phase. The described EvaporativeLimited Coalescence (ELC) process is used to control the particle sizeand distribution while a hydrocolloid is incorporated to stabilize theinner emulsion of the multiple emulsions that provide the template forgenerating the discrete pores in the porous particles.

U.S. Pat. No. 9,891,350 (Lofftus et al.) describes improved articlesthat are designed with an opacifying layer applied to a substrate andthat is capable of blocking predetermined electromagnetic radiation.

An improvement in this art is described in U.S. Pat. No. 9,469,738 (Nairet al.) in which small amounts of porous particles containing smallamounts of opacifying colorants can be incorporated into foamedcompositions that have a foam density of at least 0.1 g/cm³. Such foamedcompositions can be applied to a substrate to provide opacification.U.S. Pat. No. 9,963,569 (Nair et al) describes similar technology formaking opacifying element using a foamed aqueous latex composition.

U.S. Pat. No. 6,884,491 (Rubin et al.) describes water repellant, waterresistant, and stain resistant fabrics that are prepared using treatingcompositions that are laminated to a backing polymeric film.

U.S. Pat. No. 6,872,276 (Cherpinsky et al.) describes a process foradhesively laminating a metallized coextruded polymeric film to a fabricin the presence of a temporary support layer.

U.S. Patent Application Publication 2004/0170800 (Richards) describesblackout drapery fabrics having a metal-impregnated thermoplasticblackout film that and may be extruded or laminated to a fabric. Thereis a need for further improvement to provide a means for easily making ablackout article that can be formed by simple lamination to one side ofa fabric without having to metalize the article, and for providing testsamples of decorative black-out fabrics without making large productionbatches.

SUMMARY OF THE INVENTION

The present invention provides a method for providing an opacifyingarticle, comprising:

A) providing (i) a fabric having a face side and a back side;

B) providing (ii) an opacifying element comprising: a substrate that hasfirst and second opposing surfaces; and a dry opacifying layer that hasan inner surface and an outer surface, which dry opacifying layer isdisposed with its inner surface in contact with the first opposingsurface of the substrate,

the dry opacifying layer comprising:

(a) at least 40 weight % and up to and including 90 weight % of porousparticles, each porous particle comprising a continuous polymeric phaseand discrete pores dispersed within the continuous polymeric phase, theporous particles having a mode particle size of at least 2 μm and up toand including 50 μm and a porosity of at least 20 volume % and up to andincluding 70 volume %;

(b) at least 10 weight % and up to and including 60 weight % of a bindermaterial,

all amounts of (a) porous particles, (b) binder material, being based onthe total weight of the dry opacifying layer, and

C) laminating the (ii) opacifying element to the back side of the fabricto provide the opacifying article.

The present invention provides an opacifying element that can, ondemand, be laminated to fabrics to provide space “darkening” opacifyingarticles without the need for a latex foam or metallized layer. Suchopacifying elements can be provided in short- or long-run batches,minimizing waste of expensive fabric substrates to which the opacifyingelement can be easily applied or laminated. The present inventioneliminates the need for sewing an extra blackout liner and attaching thesame to a fabric substrate. Further, where test samples of blackoutmaterials derived from decorative fabrics are needed by designers tomock up a room, lamination or various opacifying elements on a requiredyardage of the decorative fabrics becomes more economical thansubmitting a lot of decorative fabric to a coating conversion that maynot suit the decor until after the fact. In a sense, the presentinvention provides a means for “proofing” a customer's expectationswithout using directly coated foamed opacifying compositions onto afabric substrate. The present invention enables a manufacturer or vendorto test product samples at low cost.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates partial cross-sectional views of a fabric havingface and back sides, and an opacifying element according to the presentinvention in which the opacifying element has a dry opacifying layerdisposed on a first opposing surface of a substrate.

FIG. 1B illustrates a partial cross-sectional view of an opacifyingarticle formed from the fabric and opacifying element of FIG. 1A whereinthe dry opacifying layer disposed on the first opposing surface of thesubstrate is arranged in contact with (laminated) to the back side ofthe fabric.

FIG. 2A illustrates partial cross-sectional views of a fabric havingface and back sides, and an opacifying element according to the presentinvention having a dry opacifying layer disposed the second opposingsurface of the substrate.

FIG. 2B illustrates a partial cross-sectional view of an opacifyingarticle formed from the fabric and opacifying element of FIG. 2A whereinthe dry opacifying layer disposed on the second opposing surface of thesubstrate, and the opacifying element is arranged so that the firstopposing surface of the substrate is in contact with (laminated) theback side of the fabric.

FIG. 3A illustrates partial cross-sectional views of a fabric havingface and back sides, and an opacifying element according to the presentinvention having two dry opacifying layers disposed on its first andsecond opposing surfaces.

FIG. 3B illustrates a partial cross-sectional view of an opacifyingarticle formed from the fabric and opacifying element of FIG. 3A whereinone of the dry opacifying layers disposed on the substrate is arrangedin contact with (laminated) with the back side of the fabric.

FIGS. 4A and 4B illustrate partial cross-sectional views of embodimentsof the present invention like those in FIGS. 1A and 1B except that anadhesive layer is incorporated between the fabric and opacifyingelement.

DETAILED DESCRIPTION OF THE INVENTION

The following discussion is directed to various embodiments of thepresent invention and while some embodiments can be desirable forspecific uses, the disclosed embodiments should not be interpreted orotherwise considered to limit the scope of the present invention, asclaimed below. In addition, one skilled in the art will understand thatthe following disclosure can have broader use than is explicitlydescribed or discussed for any particular embodiment.

Definitions

As used herein to define various components of the dry opacifying layer,that is the (a) porous particles, (b) binder materials, (c) opacifyingcolorant, and other materials used in the practice of this invention,unless otherwise indicated, the singular forms “a,” “an,” and “the” areintended to include one or more of the components (that is, includingplurality referents).

Each term that is not explicitly defined in the present application isto be understood to have a meaning that is commonly accepted by thoseskilled in the art. If the construction of a term would render itmeaningless or essentially meaningless in its context, the term shouldbe interpreted as having a standard dictionary meaning.

The use of numerical values in the various ranges specified herein,unless otherwise expressly indicated otherwise, are to be considered asapproximations as though the minimum and maximum values within thestated ranges were both preceded by the word “about.” In this manner,slight variations above and below the stated ranges may be useful toachieve substantially the same results as the values within the ranges.In addition, the disclosure of these ranges is intended as a continuousrange including every value between the minimum and maximum values aswell as the end points of the ranges.

Unless otherwise indicated, the terms “dry opacifying composition” and“dry opacifying layer” are intended to refer to the same feature.

The terms “porous particle” and “porous particles” are used herein,unless otherwise indicated, to refer to porous polymeric materialsuseful in the dry opacifying compositions essential for the presentinvention. The porous particles generally comprise a solid continuouspolymeric phase having an external particle surface and discrete poresdispersed within the continuous polymeric phase. The continuouspolymeric phase also can be chemically crosslinked or elastomeric innature.

The continuous polymeric phase of the porous particles generally has thesame composition throughout that solid phase. That is, the continuouspolymeric phase is generally uniform in composition including anycomponents [for example, (c) opacifying colorant] that can beincorporated therein. In addition, if mixtures of polymers are used inthe continuous polymeric phase, generally those mixtures also areuniformly distributed throughout.

As used in this disclosure, the term “isolated from each other” refersto the different (distinct) pores of the same or different sizes thatare separated from each other by some portion of the continuous solidphase and such discrete pores are not interconnected. Thus, “discrete”pores refer to “individual” or “closed” non-connected pores or voidsdistributed within the continuous polymeric phase.

The terms “first discrete pore” and “second discrete pore” refer todistinct sets of isolated discrete pores (individually isolated andclosed voids or compartments) in the (a) porous particles. Each distinctset of pores is isolated from other discrete pores in the distinct setof pores, and the discrete pores of each distinct set of pores areisolated from all other discrete pores of the other distinct sets ofpores in the (a) porous particle. Each distinct set of discrete porescan have the same mode average size or both sets can have the same modeaverage size. For making such (a) porous particles, the word “discrete”can also be used to define different droplets of the first and secondaqueous phases when they are suspended in the oil (solvent) phase(described in art cited below).

Where there are different sets of discrete pores, the discrete pores ofa first set can be predominantly nearer then external porous particlesurface compared to the discrete pores of a second set. For example, aset of smaller discrete pores can be predominantly close to the externalparticle surface compared to a set of larger discrete pores. As usedherein, the term “predominant” means that a larger number fraction ofdiscrete pores of one size is found in a “shell” area nearer the surfaceof the (a) porous particle than one would expect based on the totalnumber fraction of the two or more types (sizes) of discrete porespresent in the (a) porous particle.

The (a) porous particles can include “micro,” “meso,” and “macro”discrete pores, which according to the International Union of Pure andApplied Chemistry, are the classifications recommended for discrete poresizes of less than 2 nm, from 2 nm to and including 50 nm, and greaterthan 50 nm, respectively. Thus, while the (a) porous particles caninclude closed discrete pores of all sizes and shapes (that is, closed,non-interconnected discrete pores entirely within the continuouspolymeric phase) providing a suitable volume in each discrete pore,macro discrete pores are particularly useful. While there can be openmacro pores on the surface of the (a) porous particle, such open poresare not desirable and may be present only by accident. The size of the(a) porous particles, their formulation, and manufacturing conditionsare the primary controlling factors for discrete pore size. However,typically the discrete pores have an average size of at least 100 nm andup to and including 7,000 nm, or more likely at least 200 nm and up toand including 2,000 nm. Whatever the size of the discrete pores, theyare generally distributed randomly throughout the continuous polymericphase. However, if desired, the discrete pores can be groupedpredominantly in one part (for example, “core” or “shell”) of the (a)porous particles.

The (a) porous particles used in this invention generally have aporosity of at least 20 volume % and up to and including 70 volume %, orlikely of at least 35 volume % and up to and including 65 volume %, ormore typically of at least 40% and up to an including 60%, all based onthe total porous particle volume. Porosity can be measured by amodification of the known mercury intrusion technique.

Unless otherwise indicated, the term “non-porous” refers to particlesthat are not designed to have discrete pores or compartments within thesolid continuous polymeric phase and less than 20% of their total volumeconsists of pores.

“Opacity” is a measured parameter of an opacifying element according tothe present invention, which characterizes the extent to which thetransmission of electromagnetic radiation such as visible light isblocked. A greater opacity indicates a more efficient blocking (hiding)of electromagnetic radiation (as described below). In the presentinvention, the “opacity” of an opacifying element is quantified bymeasuring the optical density (OD), described below with the Examples,which determines the extent to which the impinging radiation or light isblocked by the opacifying element. The higher the OD, the greater thelight blocking ability exhibited by the opacifying element.

Glass transition temperature of the organic polymers used to prepare thecontinuous polymeric phase, or (b) binder materials described below, canbe measured using Differential Scanning calorimetry (DSC) using knownprocedures. For many commercially available organic materials, the glasstransition temperatures are known from suppliers.

Polymer viscosity (in centipoise or mPa-sec) of the polymers comprisingthe continuous polymeric phase can be measured in ethyl acetate atconcentration of 20 weight % of the polymer at 25° C. in an Anton ParrMCR 301 stress rheometer in a Couette cell using steady shear sweeps.Shear rate at 100 sec⁻¹ was calculated from the resulting graphical plotof viscosity vs. shear rate.

CIELAB L*, a*, and b* values described herein have the known definitionsaccording to CIE 1976 color space or later known versions of color spaceand were calculated assuming a standard D65 illuminant and knownprocedures. These values can be used to express a color as threenumerical color values: L* for the lightness (or brightness) of thecolor, a* for the green-red component of the color, and b* for theblue-yellow component of the color values.

As used herein, the term “fabric” is meant to refer to a materialcomposed of or prepared from naturally occurring fibers, syntheticfibers, or a mixture of naturally occurring fibers and synthetic fibersof any desirable length.

Uses

The method according to this invention can provide a means for easilymaking an opacifying film (or element) that can be laminated to the backside of a fabric to provide light-blocking decorative fabrics orspecific opacity and color. The opacifying articles according to thisinvention can be useful as blackout materials for various environmentsand structures. Such opacifying articles may also exhibit improved soundand heat blocking properties. They can be used as, for example, curtainsand other window treatments, carpets, window blinds, room dividers,cubicle curtains, banners, labels. projection screens, clothing,coverings and tarpaulins (for example for vehicles, boats, and otherobjects), and packaging materials. The opacifying articles canoptionally have a printable outer surface able to accept ink used inscreen printing, gravure printing, inkjet printing, thermal imaging(such as “dye sublimation thermal transfer”), or other imagingprocesses. Thus, one can provide printable surfaces in such opacifyingarticles so that the printed image on the back side (non-observer side)is generally not observable from the “face” or observer side.

Opacifying Articles

The present invention can be understood at least in part from theillustrations shown in FIGS. 1A, 1B, 2A, 2B, 3A, 3B, 4A, and 4B.

In FIG. 1A, a partial cross-section view of fabric 10 is illustrated ashaving back side 15 and face side 20. Opacifying element 25 hassubstrate 30 having first opposing surface 35 and second opposingsurface 40, and dry opacifying layer 45 having outer surface 46 andinner surface 47 that is in contact with (or disposed on) first opposingsurface 35.

FIG. 1B shows opacifying article 50 that was formed by bringing together(for example, by lamination) fabric 10 and opacifying element 25together so that outer surface 46 of dry opacifying layer 45 is arrangedin contact (for example, laminated) with back side 15 of fabric 10.

In FIG. 2A, a partial cross-section view of fabric 10 is illustrated ashaving back side 15 and face side 20. Opacifying element 55 hassubstrate 30 that has second opposing surface 60 and first opposingsurface 65. Dry opacifying layer 45 having inner surface 47 and outersurface 46, is arranged so that inner surface 47 is in contact withsecond opposing surface 60 of substrate 30.

FIG. 2B shows opacifying article 70 formed by bringing fabric 10 andopacifying element laminate 55 together (for example, by lamination) sothat first opposing surface 65 is arranged in contact with (laminatedto) back side 15 of fabric 10.

In FIG. 3A, a partial cross-section view of substrate 10 is illustratedas having back side 15 and face side 20. Opacifying element 75 hassubstrate 30 having first opposing surface 35 and second opposingsurface 80. Dry opacifying layer 45 having inner surface 47 and outersurface 46 is arranged in contact with first opposing surface 35.Opacifying element 75 also has second dry opacifying layer 85 havinginner surface 86 and outer surface 87, wherein inner surface 86 isarranged in contact with second opposing surface 80. Dry opacifyinglayer 45 and dry opacifying layer 85 can be the same or different incomposition, dry thickness, and opacifying effect.

FIG. 3B shows opacifying article 90 formed by bringing together (forexample, by lamination) fabric 10 and opacifying element 75 so that dryopacifying layer 45 is arranged with its outer surface 46 in contactwith back side 15 of fabric 10.

In FIG. 4A, a partial cross-section view of fabric 100 is illustrated ashaving back side 110, front side 115, and adhesive material 120 disposedon back side 110. Opacifying element 25 has substrate 30 having firstopposing surface 35 and second opposing surface 40, and dry opacifyinglayer 45 having outer surface 46 and inner surface 47, which is disposedon first opposing surface 35.

FIG. 4B shows opacifying article 125 formed by bringing fabric 100 andopacifying element 25 together so that outer surface 46 of dryopacifying layer 45 is arranged in contact with adhesive layer 120 thatis disposed on back side 110 of fabric 100.

Other structural embodiments not illustrated in these FIGS. are alsopossible including but not limited to an opacifying article similar toopacifying article 125 but further comprising a second dry opacifyinglayer disposed on second opposing surface 40 of substrate 30.

Moreover, an adhesive material can be disposed on outer surface 47 ofdry opacifying layer 45 rather than on back side 110 of fabric 100, orthe adhesive material can be incorporated within dry opacifying layer45. Thus, a skilled worker could design other useful structuralembodiments using this teaching and routine experimentation, all ofwhich would be within the scope of the present invention.

As illustrated in the described FIGS., the opacifying articles accordingto the present invention are generally planar in nature with smooth orirregular (with small depressions and ridges) outer surfaces.

Fabrics

Each fabric used in the practice of the present invention has a faceside (usually the viewable or observer's side) and a back side. Thesetwo opposing sides can be the same or different in appearance, texture,feel, or composition, but the back and face side labels are used todistinguish how the opacifying element is arranged in relation to thefabric as illustrated in the FIGS. noted above.

The fabric can be in the form of woven or nonwoven materials that arecomposed of naturally-occurring fibers, synthetic fibers, or mixtures ofnaturally-occurring fibers and synthetic fibers. Suitablenaturally-occurring fibers include but are not limited to, fibers ofcotton, linen, ramie, silk, wool, and others known in the natural world,and blends of fibers of such naturally-occurring materials. Suitablesynthetic fibers include but are not limited to, fibers of nylon,polyesters, acrylics, glass (fiberglass), polyurethanes, polyamides,polycarbonates, rayon, polyolefins, celluloses (include woven ornon-woven paper materials), acetates, aromatic polyamides, polyvinylchloride, and others known in the art, as well as combinations or blendsof any of these types of fibers, such as polyvinyl chloride coatedfibers of various materials. Useful fabrics can be composed of polyvinylchloride-clad polyester or polyvinyl chloride-clad fiberglass. Suitablefabric materials include but are not limited to, jacquards (that isfabrics manufactured on a jacquard loom), brocades, dobby fabrics,prints, poplins, cross-dyes, crepes, and canvasses.

In some embodiments, the fabric is a porous fabric comprising aplurality of continuous yarn strands, all woven together, wherein eachyarn strand comprises a multifilament core that is coated with a coatingcomprising thermoplastic polymer. Further details for such fabrics andtheir use are provided in copending and commonly assigned U.S. Ser. No.15/943,770 (filed Apr. 3, 2018 by Nair, Brick, and Sedita), thedisclosure of which is incorporated herein by reference.

In many embodiments, the fabric can comprise a material that has beentreated in one or more ways to provide water-repellency or stainresistance, or both. For example, such treatments can comprise applyinga suitable fluorochemical treating agent, with or without a suitableantimicrobial agent (or biocide), to the face and back sides of a fabricmaterial as well as to interstitial spaces within the fabric material,to provide a “treated” fabric, followed by suitable drying or curing atelevated temperatures. A representative treatment process is describedin Cols. 4-6 of U.S. Pat. No. 6,884,491 (noted above) as well in Cols.6ff of U.S. Pat. No. 6,541,138 (Bullock et al.), the disclosures of bothof which are incorporated herein by reference. The treatment solutionscan include one or more biocides (such as antimicrobials), crosslinkingagents (including self-crosslinking latex polymers), fire retardants,smoke suppressants, dispersants, thickeners, dyes, pigments, UV lightstabilizers, and other additives that would be readily apparent to oneskilled in the art.

For example, a fabric material can be treated with at least one or morebiocidal agents capable of destroying or preventing the activity ofbacteria, viruses, fungi, or mold, many of which materials are known inthe art, including antibiotics, trialkyl tin compounds, coppercompounds, copper complexes of dehydroabietyl amine or8-hydroxyquinolinium 2-ethylhexoate, copper naphthenate, copper oleate,organosilicon quaternary ammonium compounds, silver metal and varioussilver salts.

One or more treatments of the fabric material can be carried out toachieve the desired properties while maintaining desired hand, feel,texture, drape, and aesthetic appearance.

In general, suitable fabrics can have a dry average thickness of atleast 50 μm, and the thickness can depend upon the use of the opacifyingarticle and the type of fabric materials available for use. This dryaverage thickness can be determined when the fabric comprises less than5 weight % water (based on the total weight of the fabric) using theaverage of at least 3 measurements taken at different places, or asdetermined using a suitable micrograph image.

The fabric used in the opacifying article can also have an openness ofat least 0% and up to and including 10%, or even at least 1% and up toand including 10%. “Openness” (Openness Factor, or OF) refers to howtight the weave is in a fabric material, the percentage of holes in afabric construction, and is sometimes referred to as “weave density.”The lower the OF, the less the light transmittance and the greater thevisible light that is obstructed or blocked. It is the ratio betweentransparent and opaque surfaces and depends on the spacing and dimensionof the yarn.

Opacifying Elements

The opacifying elements used in the present invention comprise asubstrate that has first and second opposing surfaces (or two opposingplanar sides). As shown in some of the FIGS., a dry opacifying layer canbe disposed on either or both the first and second opposing surfaces.

As described above, the opacifying element is arranged in contact with(for example, laminated to) to the back side of the fabric. In someembodiments, this arrangement can mean that the opacifying element isadhered to the back side of a fabric using a suitable adhesive material(see below).

The substrate for the opacifying element generally comprises a materialwhich is suitable for a lamination process. Useful substrates can becomposed of various materials including but not limited to, synthetic ornon-synthetic (naturally-occurring) polymers or copolymers(generallyorganic materials), or blends of polymers or copolymers, and can beprovided generally in the form of a polymeric film having single ormultiple polymeric layers (such as a laminated structure).Representative useful polymeric materials include but are not limitedto, nylon or other polyamides, polyesters (such as polyethyleneterephthalate), glass, aramides, rayon, acrylics, cellulosic materials[such as triacetyl cellulose, diacetyl cellulose, acetate butyratecellulose, and acetate propionate cellulose), polyether sulfone,polyacrylic based resins [for example, poly(methyl methacrylate)],polyurethane-based resins, polycarbonates, aromatic polyamide,non-cyclic polyolefins (for example, polyethylene and polypropylene),poly(vinylidene chloride), polycaprolactams, polymers derived from vinylchloride (for example, poly(vinyl chloride) and vinyl chloride/vinylacetate copolymers), polyvinyl alcohols, polyvinyl acetates (such asethylene polyvinyl acetate), silicone resins, polystyrene and polymersderived from styrene derivatives, polysulfone, polyether, cyclic olefinpolymers such as polynorbornene, polymethylpentene, polyether ketone,(meth)acrylonitrile], and other organic polymeric film-forming materialsthat would be apparent to one skilled in the art.

The substrate can be formed of a single film such as a single polymericfilm, or it can be a “laminate” or planar composite of multiplepolymeric films composed of the same or different chemical compositionor physical properties.

Either or both the first and second opposing surfaces of the substratecan be surface treated by various processes including corona discharge,glow discharge, UV or ozone exposure, flame, or solvent washing in orderto promote desired physical properties and adhesion of a drylight-blocking composition. An adhesive material can be arranged oneither the fabric (back side) or the opacifying element to provide anintermediate adhesive layer and to promote adhesion between the fabricand opacifying elements. Useful adhesive materials are described below.

A substrate can comprise a primer layer comprising one or more polymersdesigned to promote adhesion of a dry opacifying layer, or to promoteadhesive to the fabric.

Ii may be desirable for the substrate to be “transparent” meaning thatincident radiation will pass through it with minimal absorption by thesubstrate material. This transmittance property can be measured bypassing light through the substrate and comparing the intensity of thetransmitted radiation with the intensity of the incident radiation witha UV-Vis spectrophotometer or Transparency Meter.

As described in several of the FIGS. described above, a dry opacifyinglayer according to this invention is disposed on one or both of thefirst and second opposing surfaces of the substrate. For example, asillustrated in FIG. 3A, both first and second opposing surfaces of thesubstrate can have the same or different dry opacifying layer disposedthereon. In this context, the term “different” is meant to includedifferences in composition components or amounts, layer coverages, orboth.

Each dry opacifying layer useful in the present invention has twoessential components (a) and (b) as defined below that are essential forproviding desired properties when incorporated as part of an opacifyingelement or opacifying article. However, a dry opacifying layer can havefurther advantages by the incorporation therein of an (c) opacifyingcolorant or one or more additives (e), or both (c) and (e) as definedbelow, as long as they do not interfere with the properties and purposesof the essential (a) and (b) components. Opacifying compositions used toprovide the dry opacifying layers are generally formulated in (d) waterand then applied in a suitable manner to the laminate substrate asdescribed below. An advantage of the present invention is that theseaqueous opacifying compositions are not “foamed” before theirapplication to a substrate as in prior art processes, for example asdescribed in U.S. Pat. No. 9,469,738 (noted above), thereby simplifyingthe manufacture and use of the opacifying articles according to thisinvention.

In reference to a dry opacifying layer, the term “dry” means that thelayer comprises water or auxiliary solvents (described below) in anamount of less than 5 weight %, or even less than 1 weight %, based onthe total weight of the dry opacifying layer.

Each dry opacifying layer is generally disposed on an opposing surfaceof the substrate at a dry coverage of at least 50 g/m² and up to andincluding 1000 g/m², or of at least 100 g/m² and up to and including 500g/m².

The opacifying element generally has a dry thickness of at least 100 μmor more likely of at least 300 μm, which dimension is intended toinclude the substrate, one or more dry opacifying layers, anyintermediate adhesive layer, and any other materials adhered thereto.The average dry thickness can be determined by suitably measuring theopacifying element thickness, after drying, in at least three differentplaces and taking an average of the measured values.

(a) Porous Particles:

Porous particles used in the present invention containing discrete pores(or compartments or voids) are generally prepared using one or morewater-in-oil emulsions in combination with an aqueous suspensionprocess, such as in the Evaporative Limited Coalescence (ELC) processthat is known in the art. The details for the preparation of the porousparticles are provided, for example, in U.S. Pat. No. 8,110,628 (Nair etal.), U.S. Pat. No. 8,703,834 (Nair), U.S. Pat. No. 7,754,409 (Nair etal.), U.S. Pat. No. 7,887,984 (Nair et al.), U.S. Pat. No. 8,329,783(Nair et al.), and U.S. Pat. No. 8,252,414 (Putnam et al.), thedisclosures of all of which are incorporated herein by reference. Thus,the (a) porous particles are generally polymeric and organic in nature(that is, the continuous polymeric phase is polymeric and organic innature) and non-porous particles (having less than 20% porosity) areexcluded from use in the present invention. Inorganic particles can bepresent on the outer surface of each porous particle if desired.

The (a) porous particles can be composed of a continuous polymeric phasederived from one or more organic polymers that are chosen so that thecontinuous polymeric phase has a glass transition temperature (T_(g)) ofat least 25° C., or more typically of at least 25° C. and up to andincluding 180° C., as determined using Differential Scanningcalorimetry.

The continuous polymeric phase can comprise one or more organic polymershaving the properties noted above, wherein generally at least 70 weight% and up to and including 100 weight % based on the total polymer weightin the continuous polymeric phase. In some embodiments, the continuouspolymeric phase is composed of one or more cellulose polymers (orcellulosic polymers) including but not limited to, those cellulosicpolymers derived from one or more of cellulose acetate, cellulosebutyrate, cellulose acetate butyrate, and cellulose acetate propionate.Mixtures of these cellulose polymers can also be used if desired, andmixtures comprising a polymer derived from cellulose acetate butyrate asat least 80 weight % of the total of cellulose polymers (or of allpolymers in the continuous polymeric phase) are particularly usefulmixtures. Details about such polymers are provided, for example, in U.S.Pat. No. 9,963,569 (Nair et al.), the disclosure of which isincorporated herein by reference

In other embodiments, the continuous polymeric phase can comprise one ormore organic polymers such as polyesters, styrenic polymers (for examplepolystyrene and polychlorostyrene), mono-olefin polymers (for example,polymers formed from one or more of ethylene, propylene, butylene, andisoprene), vinyl ester polymers (for example, polymer formed from one ormore of vinyl acetate, vinyl propionate, vinyl benzoate, and vinylbutyrate), polymers formed from one or more a-methylene aliphaticmonocarboxylic acid esters (for example, polymers formed from one ormore of methyl acrylate, ethyl acrylate, butyl acrylate, dodecylacrylate, octyl acrylate, phenyl acrylate, methyl methacrylate, ethylmethacrylate, butyl methacrylate, and dodecyl methacrylate), vinyl etherpolymers (such as polymers formed from one or more of vinyl methylether, vinyl ethyl ether, and vinyl butyl ether), and vinyl ketonepolymers (for example, polymers formed from one or more of vinyl methylketone, vinyl hexyl ketone, and vinyl isopropenyl ketone). Other usefulpolymers include polyurethanes, urethane acrylic copolymers, epoxyresins, silicone resins, polyamide resins, and polyesters of aromatic oraliphatic polycarboxylic acids with one or more aliphatic diols, such aspolyesters of isophthalic or terephthalic or fumaric acid with diolssuch as ethylene glycol, cyclohexane dimethanol, and bisphenol adductsof ethylene or propylene oxides. The polyesters can be saturated orunsaturated. Other useful polyesters include lactic acid polymers,glycolic acid polymers, caprolactone polymers, and hydroxybutyric acidpolymers. Details of such useful polymers are provided, for example inU.S. Pat. No. 9,891,350 (Lofftus et al.) and U.S. Pat. No. 9,469,738(Nair et al.), the disclosure of which is incorporated herein byreference.

The continuous polymeric binder of the (a) porous particles can also bederived from ethylenically unsaturated polymerizable monomers andpolyfunctional reactive compounds as described for example in U.S. Pat.No. 8,703,834 (Nair et al.), the disclosure of which is incorporatedherein by reference.

In general, the (a) porous particles used in the present invention havea mode particle size equal to or less than 50 μm, or of at least 2 μmand up to and including 50 μm, or typically of at least 3 μm and up toand including 30 μm or even up to and including 40 μm. Most useful (a)porous particles have a mode particle size of at least 3 μm and up toand including 20 μm. Mode particle size represents the most frequentlyoccurring diameter for spherical particles and the most frequentlyoccurring largest diameter for the non-spherical particles in a particlesize distribution histogram, which can be determined using knownequipment (including light scattering equipment such as the Sysmex FPIA3000 Flow Particle Image Analyzer that used image analysis measurementsand that can be obtained from various sources including MalvernPanalytical; and coulter counters and other particle characterizingequipment available from Beckman Coulter Diagnostics), software, andprocedures.

Pore stabilizing materials such as hydrocolloids can be present withinat least part of the volume of the discrete pores distributed throughoutthe continuous polymeric phase, which pore stabilizing materials aredescribed in the Nair, Nair et al., and Putnam et al. patents citedabove. For example, the pore stabilizing hydrocolloids can be selectedfrom the group consisting of carboxymethyl cellulose (CMC), a gelatin orgelatin derivative, a protein or protein derivative, polyvinyl alcoholand its derivatives, a hydrophilic synthetic polymer, and awater-soluble microgel.

It can be desired in some embodiments to provide additional stability ofone or more discrete pores in the (a) porous particles during theirformation, by having one or more amphiphilic block copolymers disposedat the interface of the one or more discrete pores and the continuouspolymeric phase. Such materials are “low HLB”, meaning that they have anHLB (hydrophilic-lipophilic balance) value as it is calculated usingknown science, of 6 or less, or even 5 or less. The details of theseamphiphilic polymers and their use in the preparation of the (a) porousparticles are provided in U.S. Pat. No. 9,029,431 (Nair et al.), thedisclosure of which is incorporated herein by reference. A particularlyuseful amphiphilic block copolymer useful in such embodiments comprisespoly(ethyleneoxide) and poly(caprolactone) that can be represented asPEO-b-PCL. Amphiphilic block copolymers, graft copolymers and randomgraft copolymers containing similar components are also useful includingother polymeric emulsifiers such as GRINDSTED® PGPR 90, polyglycerolpolyricinolate emulsifier, obtained from Danisco, Dupont.

Such an amphiphilic copolymer can be generally present in the (a) porousparticles in an amount of at least 1 weight %, or at least 2 weight %and up to and including 50 weight %, based on total (a) porous particledry weight.

The (a) porous particles used in this invention can be spherical ornon-spherical depending upon the desired use. In a method used toprepare the (a) porous particles, additives (shape control agents) canbe incorporated into the first or second aqueous phases, or in the oil(organic) phase to modify the shape, aspect ratio, or morphology of the(a) porous particles, using known technology. The (a) porous particlescan also comprise surface stabilizing agents, such as colloidal silica,on the outer surface in an amount of at least 0.1 weight %, based on thetotal dry weight of the (a) porous particle.

The average size of the discrete pores in the (a) porous particles isdescribed above.

The (a) porous particles can be provided as powders, or as aqueoussuspensions (including water or water with water-miscible organicsolvents such as alcohols). Such powders and aqueous suspensions canalso include surfactants or suspending agents to keep the (a) porousparticles suspended or for rewetting them in an aqueous medium.

The (a) porous particles are generally present in a dry opacifying layerin an amount of at least 40 weight % and up to and including 90 weight%, or typically at least 50 weight % and up to and including 70 weight%, based on the total weight of the dry opacifying layer (including anyresidual aqueous medium), particularly when the (a) porous particleshave a mode size of at least 3 μm and up to and including 20 μm.

In the dry opacifying layer, the large mismatch in refractive indexbetween the discrete pores of the (a) porous particles and the polymerwalls (continuous polymeric phase), causes incident electromagneticradiation passing through the dry opacifying layer to be scattered bythe multiplicity of interfaces and discrete pores. The back scatteredelectromagnetic radiation can again be scattered and returned in thedirection of the incident electromagnetic radiation thus reducing theattenuation and contributing to the opacifying power and brightness orluminous reflectance of the dry opacifying layer. If a small amount of(c) opacifying colorant is present in the (a) porous particles, forexample either in the discrete pores or in the continuous polymer phaseof the (a) porous particles, the opacifying power of the dry opacifyingis increased. This is because the multiple scattering of electromagneticradiation in the dry opacifying layer increases the path length of theelectromagnetic radiation through it, thereby increasing the chance thatthe electromagnetic radiation will encounter the (c) opacifying colorantand be blocked or absorbed by it.

Some particularly useful (a) porous particles comprise a continuouspolymeric phase and discrete pores dispersed within the continuouspolymeric phase, wherein:

each (a) porous particle has a mode particle size of at least 3 μm andup to and including 20 μm;

each (a) porous particle has a porosity of at least 35 volume % and upto and including 65 volume %;

the continuous polymeric phase comprises one or more polymers, in anamount of at least 70 weight %;

the average size of the discrete pores is at least 50 nm and up to andincluding 2,000 nm;

the (a) porous particles further comprise a pore stabilizinghydrocolloid within at least part of the volume of the discrete pores,which pore stabilizing hydrocolloid is selected from the groupconsisting of carboxymethyl cellulose, a gelatin, a protein or proteinderivative, polyvinyl alcohol or a derivative thereof, a hydrophilicsynthetic polymer, and a water-soluble microgel; and

the (a) porous particles comprise one or more amphiphilic low HLB blockcopolymers disposed at the interface of one or more of the discretepores and the continuous polymeric phase.

(b) Binder Materials:

The dry opacifying layer also contains one or more (b) binder materialsto hold the (a) porous particles, any (c) opacifying colorants, and any(e) additives together on the substrate.

It is particularly useful that a (b) binder material have the followingproperties: (i) it is water-soluble or water-dispersible; (ii) it iscapable of being disposed onto a suitable substrate as described below;(iii) it is capable of being dried and at least partially crosslinked(or at least partially cured); (iv) it has good light and heatstability; and (v) it is film-forming but contributes to the flexibilityof the opacifying element and is thus not too brittle, for examplegenerally having a glass transition temperature (T_(g)) of less than 25°C., or a T_(g) of less than 0° C., or of less than or equal to −10° C.,or less than or equal to −25° C., as determined using DifferentialScanning calorimetry.

The (b) binder material can include one or more organic polymers thatare film forming and that can be provided as an emulsion, dispersion, orin an aqueous solution, and that cumulatively provide the propertiesnoted above. It can also include polymers that are self-crosslinking, orit can include one or more polymers that are self-crosslinking orself-curable, or it can include one or more polymers to whichcrosslinking agents are added and are thus curable or capable of beingat least partially crosslinked under appropriate conditions.

Thus, if the (b) binder material is crosslinkable (or curable) in thepresence of a suitable crosslinking agent or catalyst, such crosslinking(or curing) can be activated chemically with heat, radiation, or otherknown means. A curing or crosslinking process serves to provide improvedinsolubility of the resulting dry opacifying layer as well as cohesivestrength and adhesion to the substrate. The curing or crosslinking agentis generally a chemical having functional groups capable of reactingwith reactive sites in a (b) binder material (such as a functionalizedlatex polymer) under curing conditions to thereby produce a crosslinkedstructure. Representative crosslinking agents include but are notlimited to, multi-functional aziridines, aldehydes, methylolderivatives, and epoxides.

Useful (b) binder materials include but are not limited, to poly(vinylalcohol), poly(vinyl pyrrolidone), ethylene oxide polymers,polyurethanes, urethane-acrylic copolymers, other acrylic polymers,styrene-acrylic copolymers, vinyl polymers, styrene-butadienecopolymers, acrylonitrile copolymers, and polyesters, silicone polymersor a combination of two or more of these organic polymers. Such (b)binder materials are readily available from various commercial sourcesor can be prepared using known starting materials and syntheticconditions. The (b) binder material can be anionic, cationic or nonionicin total charge. A useful class of film-forming (b) materials includesaqueous latex polymer dispersions such as acrylic latexes that can beionic or nonionic colloidal dispersions of acrylate polymers andcopolymers. Useful film-forming aqueous latexes includestyrene-butadiene latexes, poly(vinyl chloride) and poly(vinylidenechloride) latexes, poly(vinyl pyridine) latexes, poly(acrylonitrile)latexes, and latexes formed from acrylonitrile, butyl acrylate, andethyl acrylate.

The one or more (b) binder materials can be present in the dryopacifying layer in an amount of at least 10 weight % and up to andincluding 60 weight %, or typically at least 20 weight % and up to andincluding 50 weight %, based on the total dry opacifying layer (that is,the total weight of all components including any residual solvent).

It is useful that the dry weight ratio of the (a) porous particles tothe (b) binder material in the dry opacifying layer is at least 2:3 andup to and including 9:1, and more likely at least 1:1 and up to andincluding 3:1.

(c) Opacifying Colorants:

The use of (c) opacifying colorants in a dry opacifying layer isdesirable to block or absorb incident electromagnetic radiation withinthe range of wavelengths of at least 380 nm and up to and including 800nm. (c) Opacifying colorants can be soluble dyes or pigments, orcombinations of each or both types of materials. The amount ofelectromagnetic radiation that can be blocked or absorbed by anopacifying colorant can be determined by measuring opacity as describedbelow. The opacifying colorants can be a single colorant or acombination of materials that collectively act as the “opacifyingcolorant.”

In many embodiments, one or more (c) opacifying colorants are presentwithin the (a) porous particles, for example, within a volume of atleast some, if not all, discrete pores within the (a) porous particlesor incorporated within the continuous polymeric binder of the (a) porousparticles, or within both the volume of discrete pores and thecontinuous polymeric binder of the (a) porous particles. This is highlyadvantageous as the (a) porous particles can be used to “encapsulate”various (c) opacifying colorants as well as tinting colorants and other(e) additives (described below) so they are kept isolated from the othercomponents of the dry opacifying layer. In some embodiments, it can beuseful to incorporate (c) opacifying agents solely or additionallywithin the (b) binder material in which the (a) porous particles aredispersed.

While the (c) opacifying colorants can provide some coloration ordesired hue, they are not purposely chosen for this purpose and are thusmaterials that are chosen to be different from the optional tintingcolorants described below.

Examples of (c) opacifying colorants that can be used individually or incombination include but are not limited to, neutral or black pigments ordyes, carbon black, black iron oxide, graphite, aniline black,anthraquinone black, and combinations of colored pigments or dyes suchas cyan, magenta, yellow, green, orange, blue, red and, violet dyes. Thepresent invention is not limited to only the specific (c) opacifyingcolorants described herein but these are considered as suitable guidancefor a skilled worker to devise other combinations of (c) opacifyingcolorants for the desired absorption in a chosen range ofelectromagnetic radiation. A carbon black or neutral or black pigment ordye other than a carbon black, of which there are many types availablefrom commercial sources, is particularly useful as a (c) opacifyingcolorant.

The (c) opacifying colorant can be generally present in the dryopacifying layer in an amount of at least 0.001 weight % and up to andincluding 0.5 weight %, or even at least 0.003 weight % and up to andincluding 0.3 weight %, all based on the total weight of the dryopacifying layer (including any aqueous medium). As mixtures of thematerials can be used if desired, these amounts also refer to the totalamount of a mixture of materials used as the (c) opacifying colorant. Asnoted above, an (c) opacifying colorant can comprise a combination oftwo or more component materials (such as a combination of dyes or acombination of pigments) designed in hues and amounts so that thecombination meets the desired black-out and coloration propertiesdescribed herein.

In some embodiments, the (c) opacifying colorants, if in pigment form,are generally milled to a fine particle size and then encapsulatedwithin the volume of the discrete pores of the (a) porous particles byincorporating the milled pigment within an aqueous phase used in makingthe (a) porous particles. Alternatively, the (c) opacifying colorant canbe incorporated within the continuous polymeric phase of the (a) porousparticles by incorporating the (c) opacifying colorant in the oil phaseused in making the (a) porous particles. Such arrangements can beachieved during the manufacture of the (a) porous particles using theteaching provided herein and the teaching provided in references citedabove for making the (a) porous particles.

In some embodiments, it can be useful to incorporate at least 95% (byweight) of the total (c) opacifying colorant within the volume of the(a) porous particles (either in the discrete pores, continuous polymericphase, or both), and to incorporate the remainder, if any, within the(b) binder material. However, in many other embodiments, 100% of the (c)opacifying colorant is incorporated within the (a) porous particles. Forexample, more than 50% of the total (c) opacifying colorant can bedisposed or incorporated within the continuous polymeric phase of the(a) porous particles, and the remainder can be incorporated within thevolume of the discrete pores. Alternatively, all the (c) opacifyingcolorant can be incorporated into the volume of the discrete pores.

(d) Aqueous medium:

After the aqueous formulation (described below) has been applied to oneor both opposing surfaces of the substrate and dried, residual aqueousmedium including water or auxiliary solvents (described below) in thedry light-blocking composition is desirably less than 5 weight %, oreven less than 2 weight %, of the total dry opacifying layer weight.

(e) Optional Additives:

Optionally, the dry opacifying layer according to this invention canfurther include at least 0.0001 weight % and up to and including 20weight % and typically at least 1 weight % and up to and including 15weight %, based on the total weight of the dry opacifying layer(including any residual aqueous medium), of a combination of (e)additives that are not (a) porous particles, (c) opacifying colorants,or (b) binder materials. Such (e) additives include materials such asdispersants, plasticizers, inorganic or organic pigments and dyes (forexample, pigment or dye colorants different from the (c) opacifyingcolorants described above), flame retardants, biocides (such asfungicides and antimicrobials), preservatives, thickeners, pH buffers,optical brighteners, tinting colorants, flocking agents, thickeners, andinert inorganic and organic fillers that are not inorganic or organicpigments (colorants). The noted amounts refer to the total of all (e)additives. There can be mixtures of each type of (e) additive ormixtures of two or more types of (e) additives in each dry opacifyinglayer.

Such (e) additives are different from the (c) opacifying colorantsbecause individually or collectively, they will not substantially blockor absorb incident electromagnetic radiation in the wavelength range ofat least 380 nm and up to and including 800 nm, as determined in themanner described above for the (c) opacifying colorant.

Any of these (e) additives thereof can be present within any location ofthe dry opacifying layer, including but not limited to: the continuouspolymeric phase of the (a) porous particles; a volume of some or all thediscrete pores of the (a) porous particles; or both the volume of thediscrete pores and the continuous polymeric phase of the (a) porousparticles. Alternatively, one or more of such (e) additives can bepresent in the (b) binder material alone, or in both the (b) bindermaterial and in the (a) porous particles.

It would also be understood that while such (e) additives can be in thedry opacifying layer, and the same or different (e) additives can bepresent in the fabric described above. Thus, any (e) additive can bepresent in the same or different amounts in multiple locations in theopacifying article according to the present invention.

The “inert” inorganic or organic fillers are particles that can be addedto reduce the use of more expensive (b) binder materials. Such inertmaterials do not undergo a chemical reaction in the presence of water orother components in an aqueous formulation (described below); nor dothey absorb electromagnetic radiation like the (c) opacifying colorants.Useful inert organic or inorganic filler materials include but are notlimited to titanium dioxide, talc, clay (for example, kaolin), magnesiumhydroxides, aluminum hydroxides, dolomite, glass beads, silica, mica,glass fibers, nano-fillers, calcium carbonate, and combinations thereof.

An (e) additive can be a surfactant that is defined as a compound thatreduces surface tension in an aqueous formulation composition.

Useful biocides (that is, antimicrobial agents or antifungal agents)that can be present as (e) additives include but are not limited to,silver particles, platelets, or fibrous strands, and silver-containingcompounds such as silver chelates and silver salts such as silversulfate, silver nitrate, silver chloride, silver bromide, silver iodide,silver iodate, silver bromate, silver tungstate, silver phosphate, andsilver carboxylates. In addition, copper particles, platelets, orfibrous strands and copper-containing compounds such as copper chelatesand copper salts can be present as (e) additives for biocidal purposes.

It can also be useful to include thickeners as (e) additives to modifythe viscosity of the aqueous formulation and to control its rheology.

Useful (e) additives can comprise one or more tinting colorants that canbe used to provide a specific observable color, coloration, or hue inthe resulting dry opacifying layer. These materials are not chosen toprovide the opacifying property described below for the (c) opacifyingcolorants and thus, tinting colorants are intended to be differentmaterials having a different purpose.

Mixtures of different tinting colorants can be present. The desiredcoloration or hue can be obtained using specific tinting colorants canbe used in combination with (c) opacifying colorant(s) described belowto offset or modify the original color of an opacifying element withoutsuch materials to provide more whiteness (or brightness) in the final“color” (or coloration). The one or more tinting colorants can beincorporated within the (a) porous particles (either within the volumeof discrete pores, within the continuous polymeric phase, or in bothplaces) or they can be uniformly dispersed within the (b) bindermaterial. In some embodiments, a tinting colorant can be incorporatedwithin the same (a) porous particles that also include an (c) opacifyingcolorant. Alternatively, one or more tinting colorants can be presentwithin both the (a) porous particles (in a suitable location) and withinthe (b) binder material.

In some embodiments, a first population (set) of (a) porous particlesdescribed herein comprising (c) opacifying colorants, and anotherpopulation (set) of (a) porous particles described herein comprisingtinting colorants can be mixed with the first population of (a) porousparticles. The two sets of porous particles can comprise the same ordifferent polymers in the continuous polymeric phase.

The one or more tinting colorants can be present in the dry opacifyinglayer in an amount of at least 0.0001 weight % and up to and including 3weight %, based on the total weight of the dry opacifying layer(including residual aqueous medium). Tinting colorants can be dyes ororganic pigments that are soluble or dispersible in organic solvents andpolymers that are used for making the (a) porous particles and thus canbe included within the oil phase used to prepare such (a) porousparticles. Alternatively, the tinting colorants can be primarilywater-soluble or water-dispersible materials that are included into anaqueous phase used to prepare the (a) porous particles.

It can also be useful to include one or more optical brighteners as (e)additives to increase the whiteness (brightness or “fluorescent” effect)of the final coloration of the backside of the opacifying article.Optical brighteners are sometimes known in the art as “fluorescentwhiteners” or “fluorescent brighteners.” In general, such materials areorganic compounds selected from classes of known compounds such asderivatives of stilbene and 4,4′-diaminostilbene (such as bistriazinylderivative); derivatives of benzene and biphenyl (such as styrilderivatives); pyrazolines; derivatives of bis(benzoxazole-2-yl);coumarins; carbostyrils; naphthalimides; s-triazines; andpyridotriazoles. Specific examples of optical brighteners can be foundin various publications including “Fluorescent Whitening Agents,”Kirk-Othmer Encyclopedia of Chemical Technology, Fourth Edition, volume11, Wiley & Sons, 1994. One of more of such compounds can be present inan amount of at least 0.001 weight % and up to and including 0.5 weight%, based on the total weight of the dry opacifying layer.

When present, one or more optical brighteners can be present in one ormore materials in the dry opacifying layer. For example, an opticalbrightener can be present in the (b) binder material. Alternatively, anoptical brightener can be present within: the continuous polymeric phaseof the (a) porous particles; a volume of the first set (or any otherset) of discrete pores in the (a) porous particles; or both in a volumeof the first set (or any other set) of discrete pores and the continuouspolymeric phase, of the (a) porous particles.

Aqueous Formulations

The dry opacifying layers used in the present invention can be providedfrom corresponding aqueous formulations that can be prepared using theprocedures described below.

The essential (a) and (b) components and optional (c) opacifyingcolorants and (e) additives described above are generally present in an(d) aqueous medium in amounts different from the amounts defined abovefor the dry opacifying layer. However, the relative percentages(proportions) of the components generally should be the same as theamounts present in the dry opacifying layer.

For example, the (a) porous particles (as described above) can bepresent in an aqueous formulation in an amount of at least 5 weight %and up to and including 50 weight %, or typically of at least 20 weight% and up to and including 40 weight %, based on the total weight of theaqueous formulation.

One or more (b) binder materials can be present in the aqueousformulation in an amount of at least 10 weight % and up to and including50weight % or typically of at least 15 weight % and up to and including30 weight %, based on the total weight of the aqueous formulation.

The one or more (c) opacifying colorants (as described above) can bepresent in the aqueous formulation in an amount of at least 0.001 weight% or at least 0.001 weight % and up to and including 0.5 weight %, oreven in an amount of least 0.003 weight % and up to and including 0.2weight % especially when the opacifying colorant is a carbon black,based on the total weight of the aqueous formulation.

One or more (e) additives (as described above) can be present in theaqueous formulation in an amount of at least 0.0001 weight % and up toand including 30 weight % or typically of at least 0.001 weight % and upto and including 20 weight %, based on the total weight of the aqueousformulation.

Water is the predominant solvent used in an (d) aqueous medium in theaqueous formulations. By “predominant” is meant that of the total weightof solvents in the (d) aqueous medium, water comprises at least 75weight %, and more likely at least 80 weight % and up to and including100 weight %, of the total solvent weight. Auxiliary solvents that canbe present must not adversely affect or harm the other components in theaqueous formulation. Such auxiliary solvents can be water-miscibleorganic solvents such as alcohols and ketones.

The aqueous medium can comprise at least 30 weight % and up to andincluding 70 weight %, or typically at least 40 weight % and up to andincluding 60 weight %, of the total aqueous formulation weight.

All (a), (b), (c), and (e) components can be suitably mixed in anaqueous medium by dispersing with a cowles blade. Representative timeand temperature conditions for making such aqueous formulations would bereadily apparent to one skilled in the art.

Making Opacifying Elements

Opacifying elements can be prepared according to the present inventionby applying an aqueous formulation described above in a suitable mannerand with a suitable application means onto one or both first and secondopposing surfaces of a substrate (described above). If an aqueousformulation is applied to only one opposing surface, that opposingsurface is defined as the “first opposing surface”, and the otheropposing surface is defined as the “second opposing surface”. Asillustrated in FIGS. 1A and 1B, the dry opacifying layer on the firstopposing surface can be arranged in contact with the back side of thefabric. Alternatively, as illustrated in FIGS. 2A and 2B, a dryopacifying layer on the second opposing surface of the substrate can bearranged in contact with the back side of the fabric. As noted above,the aqueous formulation is not purposely foamed prior to its applicationto the substrate.

In some embodiments, the same or different aqueous formulations can beapplied to both first and second opposing surfaces of the substrate.

An aqueous formulation can be disposed onto an opposing surface in anysuitable manner. For example, an opposing surface of the substrate canbe coated with an aqueous formulation using suitable known coatingequipment (floating knife, hopper, blade, or gap coating apparatus) andcoating procedures including but not limited to blade coating, gapcoating such as “knife-over-roll” and “knife-over-table” operation,floating knife, slot die coating, or slide hopper coating, especially ifmultiple layers are applied to the substrate in the same operation.Thus, the aqueous formulation can be disposed directly onto an opposingsurface of the substrate wherein “directly” means there are nointervening or intermediate layers, or it can be disposed indirectlyonto the substrate, meaning that an interlayer of some type (primer oradhesive layer) is present.

Once the aqueous formulation has been disposed on an opposing surface ofthe substrate, it can be dried to remove most or all the (d) aqueousmedium that is present. Drying can be accomplished by any suitable meanssuch as by heating with warm or hot air, microwaves, or IR irradiationat a temperature and time sufficient for drying (for example, at least160° C.) to provide a dry opacifying layer.

Since the aqueous formulation is not intentionally “foamed” prior to itsapplication to the substrate, densification or crushing the applied anddry opacifying layer is not necessary.

Optional curing of the (b) binder materials can be accomplished afterdrying by heat or radiation or other conditions to which the (b) bindermaterials and any catalysts are responsive for crosslinking. In someembodiments, a suitable functionalized self-crosslinking latexcomposition is used as the (b) binder material. During this operation, acuring or crosslinking reaction can occur between reactive side groupsof suitable curable polymer chains. If the chosen (b) binder material isnot itself heat reactive, suitable catalysts and curing (crosslinking)agents can be added to the aqueous formulation to promote curing orcrosslinking.

In addition, each dry opacifying element can be designed to exhibit anL* (“brightness”) as determined using procedures described below, of atleast 60, or more likely at least 70, or even at least 90.

It is further possible to print images on an outer surface of theopacifying element after drying or curing, using any suitable printingmeans such as inkjet printing or flexographic printing, thereby formingprinted images of text, pictures, symbols, or combinations thereof. Suchprinted images can be visible, or they can invisible to the unaided eye(for example, using fluorescent dyes in the printed images).Alternatively, an outer surface can be covered by suitable means with acolorless layer to provide a desired protective finish. In manyinstances, the image formed in this manner, for example, on one outersurface, is not visible or discernible from the other outer surface ofthe opacifying element.

A thermally printed image can be formed on an outer surface, forexample, by using a thermal (sublimable) dye transfer printing process(using heat and with or without pressure) from one or more thermal donorelements comprising a dye donor layer comprising one or more dyesublimation printable colorants. For example, a thermal colorant imagecan be obtained using one or more thermal dye patches with or without athermal colorless (clear) patch. Useful details of such a process areprovided in copending and commonly assigned U.S. Ser. No. 15/590,342(filed May 9, 2017 by Nair and Herrick), the disclosure of which isincorporated herein by reference.

Preparation of Opacifying Articles

A suitable fabric as described above can be procured or provided formaking the opacifying articles according to the present invention.Additionally, a suitable opacifying element is prepared or procured asdescribed above. The opacifying element and fabric can be broughttogether into contact in any suitable manner, such as by lamination, sothat the dry opacifying layer is arranged in contact with the back sideof the fabric. These features are illustrated in FIGS. 1A and 1B.

Alternatively, as illustrated in FIGS. 2A and 2B, the second opposingsurface of the opacifying element can be arranged in contact with theback side of the fabric.

In still other embodiments, as shown in FIGS. 3A and 3B, both opposingsurfaces of the opacifying element have a dry opacifying layer disposedthereon, and either dry opacifying layer can be arranged in contact withthe back side of the fabric.

One suitable technique in which the opacifying element can be arrangedin contact with the back side of the fabric is by using an adhesivematerial such as a thin intermediate heat seal or cold seal adhesivematerial, for example as illustrated in FIGS. 4A and 4B. In someembodiments, the adhesive material is incorporated within a dryopacifying layer along with the (a) porous particles, (b) bindermaterial, and optional (c) opacifying colorant and (e) additives. Theouter surface of this dry opacifying layer can be laminated to the backside of the fabric.

When using a heat seal adhesive, the opacifying element can be suppliedfrom a suitable source (for example, a supply roll); the heat sealadhesive can be applied to the surface to be adhered; and then theopacifying element and fabric from a suitable source (for example, asecond supply roll) can be brought together. Alternatively, oradditionally, the heat seal adhesive can be supplied to the back side ofthe fabric and the two materials are brought together. In otherembodiments, a heat seal adhesive can be applied to both materialsbefore they are brought together. Or, the heat seal adhesive can besupplied (sprayed or squirted) between the two materials as they arebrought together. The heat seal adhesive, after being heated, is thenallowed to cool for example to room temperature, followed by laminatingthe opacifying element article and the fabric.

Suitable adhesive materials are known in the art, and can comprise atleast one polyamide, polyester, epoxy resin, acrylic resin, anhydridemodified polyolefin, polyurethane, or blends of two or more types ofpolymers.

Other adhesive materials can be used in the present invention includingbut not limited to use of a layer of any cold seal orpressure-sensitive, photosensitive, or thermally-sensitive adhesiveprecursor material, followed by “activation” to create an adhesive layerusing pressure, photoexposure, or thermal exposure, respectively. Forexample, liquid adhesives can be used including plastisol, epoxy,acrylic, organosol, and urethane adhesives that can be applied to eitherthe opacifying element or fabric with a suitable coating technique(gravure cylinder, knife, roller, reverse roller, or anilox roller)under heat, followed by cooling to secure the adhesive bond.

It is also possible to laminate the opacifying element and the fabricwithout the use of an intermediate adhesive layer. This can be done inany suitable manner known in the art using mechanical means without anadhesive means, using for example, direct calendar lamination to form amechanical bond between the two elements. In direct calendar lamination,the two materials are brought together for example, under heat fromappropriate sources (for example, individual supply rolls) and fedtogether into pressure rollers or a combination of calendar andembossing rollers to form the mechanical bonding upon cooling. Theresulting opacifying article can then be taken up into a roll orotherwise stored or immediately used in finishing operations.

Either or both outer surfaces of the opacifying element can be flockedto provide an attractive surface finish. In general, it can be theopposing surface that is not in contact with the back side of thefabric, that is surface finished in this manner. The dry opacifyinglayer can also be flocked. Flock refers to very short (0.1 mm and up toseveral mm) fibers that can be provided using known electrostatic ormechanical techniques. Such a surface then becomes a “flocked surface.”

Alternatively or additionally, an opposing surface of the opacifyingelement that does not have a dry opacifying layer disposed thereon canbe modified with embossing or printing to provide a suitable image orpattern using known procedures.

It may also be desirable to incorporate a dried functional compositiononto either a dry opacifying layer or opposing surface not having a dryopacifying layer. This functional composition can have any of: (i)inorganic or organic spacer particles having a mode particle size of 1to 100 μm; (ii) a solid lubricant; and (iii) a tinting material. Detailsabout such functional compositions and how they can be used are providedin U.S. Ser. No. 16/018,367 (filed Jun. 26, 2018 by Nair, Lobo, andDonovan), the disclosure of which is incorporated herein by reference.

The opacifying article provided by the present invention can have anoptical density (determined as described below) of at least 3, or evenat least 4 or at least 5.

In addition, the opacifying article can further comprise anantimicrobial agent, a flame retardant, or both types of materials,examples of which are described above for the dry opacifying layer.

In addition, the opacifying article can further comprise a surfacefinish selected from the group consisting of flock, lubricants,anti-blocking agents, antistatic agents, tactile modifiers, visualmodifiers, and soil resistance agents. Examples of such materials andthe amounts to be used are known in the textile art.

The present invention provides at least the following embodiments andcombinations thereof, but other combinations of features are consideredto be within the present invention as a skilled artisan would appreciatefrom the teaching of this disclosure:

1. A method for providing an opacifying article, comprising:

A) providing (i) a fabric having a face side and a back side;

B) providing (ii) an opacifying element comprising: a substrate that hasfirst and second opposing surfaces; and a dry opacifying layer that hasan inner surface and an outer surface, which dry opacifying layer isdisposed with its inner surface in contact with the first opposingsurface of the substrate,

the dry opacifying layer comprising:

(a) at least 40 weight % and up to and including 90 weight % of porousparticles, each porous particle comprising a continuous polymeric phaseand discrete pores dispersed within the continuous polymeric phase, theporous particles having a mode particle size of at least 2 μm and up toand including 50 μm and a porosity of at least 20 volume % and up to andincluding 70 volume %;

(b) at least 10 weight % and up to and including 60 weight % of a bindermaterial,

all amounts of (a) porous particles, (b) binder material, being based onthe total weight of the dry opacifying layer, and

C) laminating the (ii) opacifying element to the back side of the fabricto provide the opacifying article.

2. The method of embodiment 1, comprising C) laminating the outersurface of the dry opacifying layer of the opacifying element to theback side of the fabric.

3. The method of embodiment 2, comprising C) laminating the secondopposing surface of the substrate to the back side of the fabric.

4. The method of any of embodiments 1 to 3, wherein the opacifyingelement comprises a second dry opacifying layer disposed on the secondopposing surface of the substrate.

5. The method of any of embodiments 1 to 4, comprising C) laminating theopacifying element to the back side of the fabric using an adhesivematerial.

6. The method of embodiment 5, wherein the adhesive material is a heatseal adhesive or a cold seal adhesive.

7. The method of embodiment 5, wherein the adhesive material iscontained within the dry opacifying layer, the outer surface of which islaminated to the back side of the fabric.

8. The method of any of embodiments 1 to 7, comprising C) laminating theopacifying element to the back side of the fabric using mechanical meansand without an adhesive material.

9. The method of any of embodiments 1 to 8, wherein the fabric comprisesa material that has been treated prior to the C) laminating to providewater-repellency and stain resistance.

10. The method of any of embodiments 1 to 9, wherein C) laminating iscarried out by direct calendar lamination.

11. The method of any of embodiments 1 to 10, wherein the fabriccomprises an antimicrobial agent, fire retardant, or both anantimicrobial agent and a fire retardant.

12. The method of any of embodiments 1 to 11, wherein the opacifyingelement has a dry thickness of at least 100 μm.

13. The method of any of embodiments 1 to 12, wherein the substratecomprises a polymeric material selected from the group consisting ofpolyesters, cellulosic materials, non-cyclic polyolefins, cyclic olefinpolymers, polyamides, ethylene vinyl acetate, poly(vinyl chloride),poly(vinylidene chloride), and blends thereof.

14. The method of any of embodiments 1 to 13, wherein the substratecomprises one or more polymeric films.

15. The method of any of embodiments 1 to 14, wherein the (a) porousparticles have a mode particle size of at least 3 μm and up to andincluding 20 μm.

16. The method of any of embodiments 1 to 15, wherein the dry opacifyinglayer further comprises at least 0.001 weight % of (c) an opacifyingcolorant that is capable of absorbing electromagnetic radiation having awavelength of at least 380 nm and up to and including 800 nm.

17. The method of embodiment 16, wherein the (c) opacifying colorant ispresent in an amount of at least 0.001 weight % and up to and including0.3 weight %, based on the total weight of the dry opacifying layer.

18. The method of embodiment 16, wherein the (c) opacifying colorant isa carbon black, a neutral black pigment or dye other than a carbonblack, or a combination of two or more of such materials.

19. The method of embodiment 16, wherein the (c) opacifying colorant ispresent within the (a) porous particles.

20. The method of any of embodiments 1 to 19, wherein the dry opacifyinglayer further comprises one or more (e) additives selected from thegroup consisting of dispersants, plasticizers, flame retardants, opticalbrighteners, thickeners, biocides, tinting colorants, inert inorganic ororganic fillers, and a combination of any of these materials.

21. The method of embodiment 20, wherein the dry opacifying layerfurther comprises (e) one or more additives that include silverparticles or a silver salt.

22. The method of any of embodiments 1 to 21, wherein the weight ratioof the (a) porous particles to the (b) binder material in the dryopacifying layer is at least 2:3 and up to and including 9:1.

23. The method of any of embodiments 1 to 22, wherein the dry coverageof the dry opacifying layer is at least 50 g/cm² and up to and including1000 g/cm².

24. The method of any of embodiments 1 to 23, wherein the (a) porousparticles have a mode particle size of at least 3 μm and up to andincluding 20 μm and a porosity of at least 20% and up to and including65%; and a carbon black as (c) an opacifying colorant is present indiscrete pores of the (a) porous particles in an amount of at least0.003 weight % and up to and including 0.3 weight %, based on the totalweight of the dry opacifying layer.

25. The method of any of embodiments 1 to 24, wherein the fabric has anopenness of at least 0% and up to and including 10%.

26. The method of any of embodiments 1 to 25, wherein the fabric is aporous fabric comprising a plurality of continuous yarn strands, allwoven together, wherein each yarn strand comprises a multifilament corethat is coated with a coating comprising thermoplastic polymer.

The following Examples are provided to illustrate the practice of thisinvention and are not meant to be limiting in any manner.

The following materials were prepared or purchased as noted and used inthe following examples:

NEOCRYL° A-6093, an acrylic, elastomeric emulsion, used as the binderpolymer was obtained from DSM;

TERGITOL° 15-S-7 surfactant (Dow Chemical Company), a secondary alcoholsurfactant having an HLB value of 12.4, was obtained from the DowChemical Corp.;

White woven fabric material used as the “fabric” in the opacifyingarticles was a woven poplin that had a thickness of 0.0076 inches (0.02cm).

The substrate used for creating the opacifying elements was apoly(ethylene terephthalate) film having a thickness of 0.0005 inches(0.0127 mm).

Preparation of (a) Porous Particles:

The (a) porous particles used for preparing the opacifying element andopacifying article for each Invention Example are described below alongwith the characteristics of the particles. All (a) porous particlescontained 1 weight % of optical brightener in the continuous polymericphase.

Porous particles PX containing 0.1 weight % of (c) opacifying colorant(carbon black) in the discrete pores and cellulose acetate butyrate inthe continuous polymeric phase were prepared as described in U.S. Pat.No. 9,963,569 (Nair et al.). The resulting (c) porous particles had aparticle size of 5μm and a porosity of 43%.

Porous particle PY containing 0.05 weight % of (c) opacifying colorant(carbon black) in the discrete pores and cellulose acetate butyrate inthe continuous polymeric phase were prepared as described in U.S. Pat.No. 9,963,569 (noted above). The resulting (a) porous particles had aparticle size of 5.7 μm and a porosity of 49.5%.

Measurements:

The mode particle size of the (a) porous particles was measured using aSysmex FPIA-3000 Flow Particle Image Analyzer available from MalvernPanalytical. The particle size of the dispersed pigments was determinedusing light scattering.

The porosity of the (a) porous particles was measured using a modifiedversion of the known mercury intrusion porosimetry method.

The light blocking ability of each opacifying article in the Examples,in transmitted light, was evaluated by measuring its optical density(OD) using a custom-built apparatus consisting of a fiber optic Xenonlight source, a computer controlled translational stage, and an opticalphotometer. The fiber optic was positioned 10 mm above the surface ofthe opacifying element. A photodetector was placed on the other side ofeach opacifying article directly under the fiber optic to quantify theamount of light that passed through the opacifying article. The opticaldensity (OD) of each opacifying article was calculated by comparing thelight that passed through the opacifying article to the light thatreached the detector when the opacifying article was not present.

The luminous reflectance (or brightness) of each opacifying element wasdetermined by first measuring the spectral reflectance in the 400-700 nmwavelength range using a Hunter Labs UltraScan XE colorimeter equippedwith an integrating sphere and a pulsed Xenon light source andappropriate filters for standard D65 illumination with the opacifyingelement facing the light source, either the dry opacifying layer of thesubstrate side of the opacifying element. A light trap and standardwhite tile were used to fix the percent reflectance range from 0 to100%. The X, Y, and Z tristimulus values of each opacifying element werealso determined and used in conjunction with the CIELab color space tocalculate specific values for the lightness (L*), red-green character(a*), and yellow-blue character (b*) of each opacifying element. The Ytristimulus value was used as a measure of the luminous reflectance orbrightness of each opacifying element.

Invention Examples 1a and 1b:

An aqueous composition was prepared by combining 19.4 weight % ofNEOCRYL® A-6093 binder polymer, 0.9 weight % of TERGITOL® 15-S-7surfactant, water, and 29.4 weight % of porous particles PX (having 0.1%carbon black in the discrete pores) in a container. The aqueousformulation was mixed with a Cowles blade until all porous particleswere well dispersed, then de-gassed to remove large bubbles so there isno foam in this formulation. The resulting mixed aqueous composition wascoated using a blade with a 0.024 inch (0.61 mm) gap onto a substrate(described above) and dried at 35° C. to form a dry opacifying layer onthe laminate. The dry opacifying layer had a total dry coverage of 201g/m² (5.9 oz/yd²) and 0.06 weight % of carbon black. The resultingopacifying element laminate was laminated to the back side of a whitewoven fabric having a thickness of 0.0076 inches (0.02 cm) with the dryopacifying layer in contact with the fabric back side, to form anopacifying article (Invention Example 1a) according to the presentinvention.

The second opposing surface of a sample of the same opacifying elementwas also laminated to the back side of the white woven fabric with thedry opacifying layer facing away from the fabric, to form anotheropacifying article according to the present invention (Invention Example1b).

Lamination was carried out for both Examples using a double-sidedpressure sensitive, optically clear 2 mil (0.05 mm) adhesive film havingpeelable liners on both sides. The adhesive film was first applied tothe opacifying element and then to the fabric back side.

Invention Examples 2a and 2b:

Invention Example 2 was prepared the same manner as Invention Example 1aexcept porous particles PY contained 0.05% of carbon black in thediscrete pores were used. The aqueous composition was coated and driedin the same manner as for Invention Example 1a. The final dry opacifyinglayer in the opacifying element had a total dry coverage of 201 g/m² and0.03 weight % of carbon black. The opacifying element was laminated withthe dry opacifying layer in contact with the back side of a white wovenfabric to form an opacifying article (Invention Example 2a) according tothe present invention.

A portion of this opacifying article was also flocked by applying anadhesive to the opposing surface of the opacifying element facing awayfrom the fabric, followed by application of 0.1 mm cotton flock onto theadhesive with a hand-held sieve. The flocked surface had a fabric-likefeel compared to a non-flocked sample of the same opacifying article.

Invention Example 3:

Invention Example 3 was prepared in the same manner as Invention Example1a except a 50/50 weight % mixture of porous particles PX and PY wasused. The aqueous composition was coated and dried in the same manner asfor Invention Example 1a. The dry opacifying layer contained a total drycoverage of 201 g/m² and 0.04 weight % of carbon black. The resultingopacifying element was laminated to the back side of a white wovenfabric with the dry opacifying layer in contact with the fabric backside.

The optical densities of the various opacifying articles and thecolorimetric data of the opacifying elements are shown in TABLE I,wherein all the parameters are as described above. The data for thefabric alone is also shown in the following TABLE I.

TABLE I Optical Density (OD) L* a* b* Y Fabric only 0.54 84.0 2.6 −10.764.1 Invention 7.1 77.8 2.2 −5.1 52.8 Example 1a Invention 6.5 75.7 2.5−5.4 49.3 Example 1b Invention 4.1 83.5 2.2 −5.9 63.1 Example 2aInvention 4.1 84.1 2.7 −7.5 64.2 Example 2b, Flocked Invention 5.4 80.72.1 −5.3 57.9 Example 3 NA = not applicable

The examples and data in TABLE I indicate that opacifying articles canbe prepared by laminating an opacifying element containing porousparticles to a fabric according to the present invention, and allopacifying articles exhibited good light blocking with opticaldensities >4 compared to the fabric alone. The L*, a*, and b* valuesdescribe the properties of the surface of the opaque element in eachexample, such as the exposed surface of the dry opacifying layer, or thesubstrate side of the opacifying element, or the flocked surface of theopacifying element. In spite of their high opacity, the opacifyingelements exhibited L* values >70. They also exhibited a high degree ofwhiteness as indicated by the Y tristimulus value of luminousreflectance greater than 45.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be achieved within the spirit and scopeof the invention.

PARTS LIST

-   10 fabric-   15 back side-   20 face side-   25 opacifying element-   30 substrate-   35 first opposing surface-   40 second opposing surface-   45 dry opacifying layer-   46 outer surface-   47 inner surface-   50 opacifying article-   55 opacifying element-   60 second opposing surface-   65 first opposing surface-   70 opacifying article-   75 opacifying element-   80 second opposing surface-   85 second dry opacifying layer-   86 inner surface-   87 outer surface-   90 opacifying article-   100 fabric-   110 back side-   115 face side-   120 adhesive material-   125 opacifying article

1. A method for providing an opacifying article, comprising: A)providing (i) a fabric having a face side and a back side; B) providing(ii) an opacifying element comprising: a substrate that has first andsecond opposing surfaces; and a dry opacifying layer that has an innersurface and an outer surface, which dry opacifying layer is disposedwith its inner surface in contact with the first opposing surface of thesubstrate, the dry opacifying layer comprising: (a) at least 40 weight %and up to and including 90 weight % of porous particles, each porousparticle comprising a continuous polymeric phase and discrete poresdispersed within the continuous polymeric phase, the porous particleshaving a mode particle size of at least 2 μm and up to and including 50μm and a porosity of at least 20 volume % and up to and including 70volume %; (b) at least 10 weight % and up to and including 60 weight %of a binder material, all amounts of (a) porous particles, (b) bindermaterial, being based on the total weight of the dry opacifying layer,and C) laminating the (ii) opacifying element to the back side of thefabric to provide the opacifying article.
 2. The method of claim 1,comprising C) laminating the outer surface of the dry opacifying layerof the opacifying element to the back side of the fabric.
 3. The methodof claim 2, comprising C) laminating the second opposing surface of thesubstrate to the back side of the fabric.
 4. The method of claim 1,wherein the opacifying element comprises a second dry opacifying layerdisposed on the second opposing surface of the substrate.
 5. The methodof claim 1, comprising C) laminating the opacifying element to the backside of the fabric using an adhesive material.
 6. The method of claim 5,wherein the adhesive material is a heat seal adhesive or a cold sealadhesive.
 7. The method of claim 5, wherein the adhesive material iscontained within the dry opacifying layer, the outer surface of which islaminated to the back side of the fabric.
 8. The method of claim 1,comprising C) laminating the opacifying element to the back side of thefabric using mechanical means and without an adhesive material.
 9. Themethod of claim 1, wherein the fabric comprises a material that has beentreated prior to the C) laminating to provide water-repellency and stainresistance.
 10. The method of claim 1, wherein C) laminating is carriedout by direct calendar lamination.
 11. The method of claim 1, whereinthe fabric comprises an antimicrobial agent, fire retardant, or both anantimicrobial agent and a fire retardant.
 12. The method of claim 1,wherein the opacifying element has a dry thickness of at least 100 μm.13. The method of claim 1, wherein the substrate comprises a polymericmaterial selected from the group consisting of polyesters, cellulosicmaterials, non-cyclic polyolefins, cyclic olefin polymers, polyamides,ethylene vinyl acetate, poly(vinyl chloride), poly(vinylidene chloride),and blends thereof.
 14. The method of claim 1, wherein the substratecomprises one or more polymeric films.
 15. The method of claim 1,wherein the (a) porous particles have a mode particle size of at least 3μm and up to and including 20 μm.
 16. The method of claim 1, wherein thedry opacifying layer further comprises at least 0.001 weight % of (c) anopacifying colorant that is capable of absorbing electromagneticradiation having a wavelength of at least 380 nm and up to and including800 nm.
 17. The method of claim 16, wherein the (c) opacifying colorantis a carbon black, a neutral black pigment or dye other than a carbonblack, or a combination of two or more of such materials.
 18. The methodof claim 1, wherein the dry opacifying layer further comprises one ormore (e) additives selected from the group consisting of dispersants,plasticizers, flame retardants, optical brighteners, thickeners,biocides, tinting colorants, inert inorganic or organic fillers, and acombination of any of these materials.
 19. The method of claim 1,wherein the weight ratio of the (a) porous particles to the (b) bindermaterial in the dry opacifying layer is at least 2:3 and up to andincluding 9:1.
 20. The method of claim 1, wherein the dry coverage ofthe dry opacifying layer is at least 50 g/cm² and up to and including1000 g/cm².